Macedonian front

The Macedonian front was a theater of the Balkan front of World War I which was active from 21 October 1915 to 30 September 1918 as Allied troops assisted the remnants of the Serbian army in fighting the Bulgarian-led Central Powers armies in Macedonia. The front was largely inactive until 1918, when Allied forces launched a major offensive against the Central Powers with the goal of knocking Bulgaria out of the war. The Allied advance pushed the Bulgarian armies back and led to King Ferdinand I of Bulgaria's government rebelling against him by forcing him to sign an armistice on 30 September.

Background
Bulgarian troops helped defeat Serbia in autumn 1915 and Romania the following year. In autumn 1915, Allied forces landed at Salonika in northern Greece, across the border from Bulgaria and Serbia. Greece entered the war on the Allied side in June 1917.

Campaign
The troops of the multinational Allied army established in the Macedonian region of northern Greece from October 1915 were dubbed the "gardeners of Salonika" because of their relative inactivity. Despite intermittent offensives and counteroffensives, the Macedonian front remained largely passive, with far heavier losses to disease than combat.

The arrival of a new commander, the French General Louis Franchet d'Esperey, in June 1918 shook the Allied army out of its torpor. His force of French, British, Greek, Serbian, Italian, and Czech troops numbered over half a million. The Bulgarian forces entrenched opposite the Allies were similar in number but had been demoralized by the withdrawal of German military support since spring 1918, when all German resources were redeployed to the Western Front.

Franchet d'Esperey planned a two-pronged operation. French and Serbian troops would lead a surprise offensive through mountainous southern Serbia, while British and Greek forces attacked farther east at Lake doiran, a site of earlier fighting that was well fortified by its Bulgarian defenders.

The French and Serbians launched their attack on 15 September and advanced 19 miles in three days. At Lake Doiran, the Bulgarians repulsed the British and Greeks on 18-19 September, inflicting heavy losses on infantry mounting frontal assaults. However, the Bulgarians were immediately forced to withdraw from the Lake Doiran region in an attempt to block the French and Serbian advance from the west. Earlier in the war, German forces would have been swiftly deployed to the Macedonian front to stabilize the situation, but none were now available.

Antiwar demonstrations broke out in Bulgarian towns as the military situation deteriorated. Bulgaria's King Ferdinand I wanted a fight to the death, but his government requested an armistice. This came into force on 30 September. The collapse of Bulgaria left the Allies free to attack Austria-Hungary to the north or the Turkish capital Constantinople to the east.

Aftermath
The collapse of Bulgaria left the Central Powers with an undefended southern front. The Allies advanced northward through Serbia and captured Belgrade on 1 November. With no troops available to prevent an Allied invasion of their countries, both Austria-Hungary and Germany sought a way to end the war. Austria-Hungary signed an armistice on 3 November, four days after Turkey, and Germany followed suit on 11 November.